Patent GB-847661-A (GB)
Title: Improved polymerization process and products thereof
IPC: C08F10/00
Filed: 1957-03-20
Abstract: Catalysts for the low pressure polymerisation of olefin are formed (see Group III) by reducing a halide of a Group IV, V, VI or VIII transition metal with a metallic reducing agent so as to form a mixture of the reduced halide of the transition metal with a halide of a Group II or III metal, and subsequently activating the mixture of halides with an alkyl compound of a Group II or III metal.  The alkyl group is preferably derived from the olefin to be polymerised. In an example of batch polymerisation of propylene in xylene, the catalyst components (Ti Cl3 preparation containing Al Cl3 and triethylaluminium as activator) were added to a reactor with dry xylene and stirred for 40 mins. at room temperature.  More dry xylene was then added, the gaseous propylene feed started and the temperature slowly raised until maximum polymerisation rate was obtained, which in the example was 102 DEG  C. yielding 23 gms. polymer/gm. catalyst/hour. More xylene was added as needed for good stirring.  The final product was solid polypropylene of high crystallinity containing at least 85% heptane-insoluble constituents and having a Harris mol. wt. of at least 85,000.ALSO:A catalyst for low pressure polymerization of olefins is formed by reducing a halide of a Group IV, V, VI or VIII transition metal with a metallic reducing agent so as to form a mixture of the reduced halide of the transition metal with a halide of a Group II or III metal, and subsequently activating the mixture of halides with an alkyl compound of a Group II or III metal.  The Group II or III metal halide is preferably aluminium, magnesium or zinc chloride or bromide, and the same metals are preferably p  used for the activator.  The amount of metal used is preferably such that after reduction, a small excess of free metal is left in the product.  The reduction is preferably carried out at 250-500 DEG C. under a pressure of 2-30 atmospheres for 1-30 hours. The transition metal halide is preferably titanium chloride.  The Group II or III metal halide is preferably aluminium chloride used in an amount of 1-70 mole per cent, so as to leave 5-50 mole per cent aluminium chloride in the final product.  The metal alkyl activator is preferably aluminium triethyl, tripropyl or triisobutyl used in a mole ratio of 1-10 at 20-40 DEG C. with agitation, but other alkyl compounds may be used, e.g. aluminium dialkyl monohalides or other substituted aluminium alkyl compounds such as methoxy aluminium diethyl or derivatives having the general formula AlR2X where X may be a secondary amine, acid amide, mercaptan or thiophenol.  Preferably, the alkyl group is derived from the olefin to be polymerized.  In an example, purified TiCl4, dry Ti powder and anhydrous AlCl3 were heated in a steel bomb with agitation at 400 DEG C. for 24 hours, and a violet-purple preparation of TiCl3 and AlCl3 was obtained of microcrystalline form.  Similar examples employ TiCl4, granular Al and AlCl3 were used as starting materials. Examples are given (see Group IV(a)) of the production of polypropylene using the new catalysts.